Although forest and savanna biomes predominate in tropics regions, the factors that control their distribution remain unclear. South American savannas occur in regions that are considered warm and humid enough to support forests, indicating that agents other than climate determine the occurrence of one or the other physiognomy. Herbivory, fire and water deficit have been considered environmental filters that limit the forest species encroachment in savanna physiognomies, but the effects of these filters on the capability of these species to recruit from seeds remain poorly understood. In this study we investigated how stress factors characteristic of savanna environments, such as soil desiccation, heat shocks and high temperatures affect the survival and germination of seeds from savanna and forest tree species. We found that desiccation (to 5%) reduced the germination percentage of forest seeds, but had no effect on the germination of savanna seeds. Forest seeds were less tolerant to heat shocks of 140°C and 200°C, and showed lower germination percentage at temperatures of 35 and 40°C, when compared with savanna seeds. Savanna seeds presented longer germination times and higher germination variance than forest seeds, indicating a risk-spreading germination strategy among savanna species. The low tolerance of forest seeds to desiccation, heat shock and high temperatures may explain the low recruitment of forest trees into savanna physiognomies. Climate change models predict lower soil moisture, higher temperatures and higher fires frequency for South America biomes. Our results suggest that savanna species are likely to be more capable of withstanding the effects of these changes than forest species. METHODS Study areaSeeds were collected at the IBGE (Brazilian Institute for Geography and Statistics) Ecological Reserve (15°55′-15°58′S, 47°52′-47°55′W) and at the adjacent experimental farm Fazenda Água Limpa (FAL) (15°56′-15°59′S, 47°55′-47°58′W), both located near Brasília, DF, Brazil, at 268 L. C. RIBEIRO AND F. BORGHETTI

SUMMARYPurpose: In the present study we decided to investigate whether physical exercise protects against the electrographic, oxidative, and neurochemical alterations induced by subthreshold to severe convulsive doses of pentyltetrazole (PTZ). Methods: The effect of swimming training (6 weeks) on convulsive behavior induced by PTZ (30, 45, and 60 mg/kg, i.p.) was measured and different electrographic electroencephalography (EEG) frequencies obtained from freely moving rats. After EEG recordings, reactive oxygen species (ROS) generation, nonprotein sulfhydryl (NPS), protein carbonyl, thiobarbituric acid-reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), Na + , K + -ATPase activity, and glutamate uptake were measured in the cerebral cortex of rats. Results: We showed that physical training increased latency and attenuated the duration of generalized seizures induced by administration of PTZ (45 mg/kg). EEG recordings showed that physical exercise decreased the spike amplitude after PTZ administration (all doses). Pearson's correlation analysis revealed that protection of physical training against PTZ-induced seizures strongly correlated with NPS content, Na + , K + -ATPase activity, and glutamate-uptake maintenance. Physical training also increased SOD activity, NPS content, attenuated ROS generation per se, and was effective against inhibition of Na + , K + -ATPase activity induced by a subthreshold convulsive dose of PTZ (30 mg/kg). In addition, physical training protected against 2¢,7¢-dichlorofluorescein diacetate (DCFH-DA) oxidation, TBARS and protein carbonyl increase, decrease of NPS content, inhibition of SOD and catalase, and inhibition glutamate uptake induced by PTZ. Conclusions: These data suggest that effective protection of selected targets for free radical damage, such as Na + , K + -ATPase, elicited by physical training protects against the increase of neuronal excitability and oxidative damage induced by PTZ.

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Increasing evidence suggests that plant-derived extracts and their isolated components are useful for treatment of seizures and, hence, constitute a valuable source of new antiepileptic drugs with improved efficacy and better adverse effect profile. β-Caryophyllene is a natural bicyclic sesquiterpene that occurs in a wide range of plant species and displays a number of biological actions, including neuroprotective activity. In the present study, we tested the hypothesis that β-caryophyllene displays anticonvulsant effects. In addition, we investigated the effect of β-caryophyllene on behavioral parameters and on seizure-induced oxidative stress. Adult C57BL/6 mice received increasing doses of β-caryophyllene (0, 10, 30, or 100mg/kg). After 60 min, we measured the latencies to myoclonic and generalized seizures induced by pentylenetetrazole (PTZ, 60 mg/kg). We found that β-caryophyllene increased the latency to myoclonic jerks induced by PTZ. This result was confirmed by electroencephalographic analysis. In a separate set of experiments, we found that mice treated with an anticonvulsant dose of β-caryophyllene (100mg/kg) displayed an improved recognition index in the object recognition test. This effect was not accompanied by behavioral changes in the open-field, rotarod, or forced swim tests. Administration of an anticonvulsant dose of β-caryophyllene (100mg/kg) did not prevent PTZ-induced oxidative stress (i.e., increase in the levels of thiobarbituric acid-reactive substances or the decrease in nonprotein thiols content). Altogether, the present data suggest that β-caryophyllene displays anticonvulsant activity against seizures induced by PTZ in mice. Since no adverse effects were observed in the same dose range of the anticonvulsant effect, β-caryophyllene should be further evaluated in future development of new anticonvulsant drugs.

Nomenclature Lista de Esp ecies da Flora do BrasilAbstract Questions: Does seed mass influence the tolerance of seeds to the effects of heating in fires? Is the tolerance to heat shocks during fire events dependent mostly on seed mass itself or to other traits linked to the species ecological origin, e.g. non-fire-prone (forest) and fire-prone (savanna) environments?Location: Savanna and forest ecosystems of the Cerrado biome, Brazil.Methods: Heat shocks were applied to seeds of 17 selected common tree species in savanna (ten species) or forest ecosystems (seven species) of the Cerrado biome. After being submitted to a heat shock, seeds were allowed to germinate in chambers set at 30°C. Germination percentage was calculated for each treatment and species. For comparison purposes, species were grouped into two functional groups (forest and savanna) and also into seed size classes (small, medium and large). We used generalized linear model to analyse heat shock effects on seed germination of savanna and forest tree species, and how seed size affected the germination response.Results: Seed mass influenced seed tolerance to heat shock. Larger seeds had higher survival when subjected to heat shock, independent of species' ecological origin. In addition, seeds from species occurring in fire-prone environments (savanna) were more tolerant to high levels of heat shock than seeds from species occurring in non-fire-prone environments (forest). Conclusion:In response to global climatic change, fire regimes in savannas of South America are expected to become more frequent and intense, even expanding into currently non-fire-prone environments. In this sense, our findings indicate that species from savannas (fire-prone environments) might have an adaptive advantage to these consequences of climatic changes, potentially leading to expansion of the savanna ecosystems.

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New control methods are necessary for stored grain pest management programs due to both the widespread problems of insecticide-resistance populations and the increasing concerns of consumers regarding pesticide residues in food products. Thus, this study evaluated the bioactivity of extracts and fractions obtained from different structures (leaves, branches, and seeds) of Annona mucosa (Annonaceae) against Sitophilus zeamais (Coleoptera: Curculionidae), which is a primary insect pest of stored cereals in tropical conditions. In the screening assay, the most promising treatments were extracts prepared from the seeds of Annona mucosa in hexane and dichloromethane (LC 90 values of 259.31 and 425.15 mg kg À1 , respectively) and, to a lesser extent, an extract prepared from the leaves in hexane (LC 90 of 1047.15 mg kg À1). Based on these results and the chromatographic profile of the bioactive crude extracts, the extract prepared from the seeds in hexane was fractionated by liquideliquid partitioning. The dichloromethane and hydroalcoholic fractions exhibited insecticidal activity against S. zeamais, and no significant difference was observed between these two fractions. The chemical analyses (1 H NMR, HPLC, and TLC) showed the presence of alkaloids and acetogenins in the bioactive fractions, which are likely related to the observed bioactivity. Thus, A. mucosa, particularly its seeds, is a promising source of compounds that can be used as a prototype model and/or a biorational insecticide for the control of S. zeamais in stored cereals.